Question

If a diver surfaces too quickly, he may suffer the bends. Nitrogen (氮) dissolved (溶解) in his blood is suddenly liberated by the reduction of pressure. The consequence, if the bubbles (氣泡) accumulate in a joint, is sharp pain and a bent body—thus the name. If the bubbles form in his lungs or his brain, the consequence can be death.

Other air-breathing animals also suffer this decompression (減壓) sickness if they surface too fast: whales, for example. And so, long ago, did ichthyosaurs. That these ancient sea animals got the bends can be seen from their bones. If bubbles of nitrogen form inside the bone they can cut off its blood supply. This kills the cells in the bone, and consequently weakens it, sometimes to the point of collapse. Fossil (化石) bones that have caved in on themselves are thus a sign that the animal once had the bends.

Bruce Rothschild of the University of Kansas knew all this when he began a study of ichthyosaur bones to find out how widespread the problem was in the past. What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompression over the 150 million years. To this end, he and his colleagues traveled the world’s natural-history museums, looking at hundreds of ichthyosaurs from the Triassic period and from the later Jurassic and Cretaceous periods.

When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression. Instead, he was astonished to discover the opposite. More than 15% of Jurassic and Cretaceous ichthyosaurs had suffered the bends before they died, but not a single Triassic specimen (標(biāo)本) showed evidence of that sort of injury.

If ichthyosaurs did evolve an anti-decompression means, they clearly did so quickly—and, most strangely, they lost it afterwards. But that is not what Dr Rothschild thinks happened. He suspects it was evolution in other animals that caused the change.

Whales that suffer the bends often do so because they have surfaced to escape a predator (捕食動物) such as a large shark. One of the features of Jurassic oceans was an abundance of large sharks and crocodiles, both of which were fond of ichthyosaur lunches. Triassic oceans, by contrast, were mercifully shark- and crocodile-free. In the Triassic, then, ichthyosaurs were top of the food chain. In the Jurassic and Cretaceous, they were prey (獵物) as well as predator—and often had to make a speedy exit as a result.

61. Which of the following is a typical symptom of the bends?

A. A twisted body.

B. A gradual decrease in blood supply.

C. A sudden release of nitrogen in blood.

D. A drop in blood pressure.

62. The purpose of Rothschild’s study is to see ______.

A. how often ichthyosaurs caught the bends

B. how ichthyosaurs adapted to decompression

C. why ichthyosaurs bent their bodies

D. when ichthyosaurs broke their bones

63. Rothschild’s finding stated in Paragraph 4 ______.

A. confirmed his assumption                    B. speeded up his research process

C. disagreed with his assumption            D. changed his research objectives

64. Rothschild might have concluded that ichthyosaurs ______.

A. failed to evolve an anti-decompression means

B. gradually developed measures against the bends

C. died out because of large sharks and crocodiles

D. evolved an anti-decompression means but soon lost it

Answer 1

語篇解讀：本篇為科普說明文，講的魚龍的身體彎曲的原因和后果。Dr Rothschild通過實驗推翻了關(guān)于魚龍進化的一些猜測。

段落	關(guān)鍵詞、句	大意概括
第一部分 （Para. 1-2）	Nitrogen dissolved; the reduction of pressure; sharp pain and a bent body; death; Other air-breathing animals; decompression; sickness	壓力減少導(dǎo)致的氮溶解；結(jié)果時劇痛和彎曲，甚至死亡。其它動物也會遭受減壓疾病。
第二部分 （Para. 3-6）	Rothschild began a study; he assumed…; Instead, he was astonished to discover…; he suspects…	Rothschild開始一項調(diào)查；他先假設(shè)；然后驚奇發(fā)現(xiàn)結(jié)果并非如此；他懷疑……

61. A。細節(jié)理解題。根據(jù)the bends可定位到首段。由The consequence…is sharp pain and a bent body—thus the name.可知答案，a bent body和a twisted body是同義轉(zhuǎn)換。由第二句的“…suddenly liberated by the reduction of pressure.”可知這是說the bends的形成原因，故C和D項錯，而B項文章沒有提及。

62. B。推理判斷題。題干中的關(guān)鍵詞是Rothschild’s study。由此可定位到第三段的前兩句。根據(jù)to find out how widespread the problem was in the past和to investigate was how ichthyosaurs adapted to the problem of decompression可知答案為B。其它各項與Rothschild’s study沒有關(guān)系。

63. C。推理判斷題。第四段開始說到he assumed that signs of the bends would be rarer in younger fossils，接下來又說Instead, he was astonished to discover the opposite。可見，他的實驗結(jié)果和他開始的預(yù)測相反，故C項符合。instead是一個轉(zhuǎn)換話題的標(biāo)志詞，一般為題眼所在。

64. A。推理判斷題。由倒數(shù)第二段的If ichthyosaurs did evolve an anti-decompression means…But that is not what Dr Rothschild thinks happened.可知，Dr Rothschild并不認可魚龍的抗溶解進化途徑。故A項符合。B項文章沒有提及；文章只是說they have surfaced to escape a predator，并不是說魚龍的滅絕是鯊魚造成的；D項與Dr Rothschild的看法正好相反。

【難句學(xué)習(xí)】

1. The consequence, if the bubbles (氣泡) accumulate in a joint, is sharp pain and a bent body—thus the name.

翻譯：如果氣泡在一個關(guān)節(jié)處累積，后果就是劇痛和彎曲的身體——因此它的名字就這樣產(chǎn)生了。

分析：本句中的if引導(dǎo)的狀語從句是插入語，主干是The consequence is sharp pain and a bent body。

2. When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression.

翻譯：開始時，他假設(shè)彎曲的跡象在年紀輕的化石中會少見，這也反映在針對減壓的措施中他們的逐漸進化。

分析：本句主干是he assumed that…。when引導(dǎo)時間狀語從句，reflecting是現(xiàn)在分詞結(jié)構(gòu)作結(jié)果狀語。